Bill,
Looking back over your quest to find his training location -I'm not sure your understanding of technical level is correct for that corresponding to his changing RAF role.
The RAF as a technical service was divided into trade groups where roles of similar skill level were combined. Pay was determined by not only rank but also trade group.
The most skilled trade group was I or 1 and the least skilled V or 5.
His first mustering was ACH / Radio Op 5. 31/7/40 ie Group 5
Other example trades in this group were Driver MT, Pigeon Keeper, Batman, Parachute Packer, Telephone Operator. All trades that did not have a formal training school but were instructed on the task.
His next mustering was Radio op 4 . 15/8/40 ie Group 4
Example trades in Group 4 were Teleprinter Operator, Equipment Assistant, Clerk (All types), Radio Telephony Operator (eg no Morse - voice procedure only)
Group 3 was fabric workers, cook butcher, shoe maker, balloon riggers etc.
It was not until after three years on the job training that he reached Group 2 - Radar Op 2. 2/9/43
Also in Group 2 were Flight Mechanics, Wireless/Radio Operators, armourer etc.
To complete the story in case others are wondering Grade 1 included Fitters, Wireless Mechanics, Radio mechanics, Blacksmith and welder.
To sum up his training was not formal in a class room but gradual improvement of knowledge and skill over several years moving him from repetitive action only to understanding the underlying principles and able to swap out equipment modules but not including the skills necessary for component fault finding and repair.
Regards
Ross